I honestly think that you should carefully think about what you might need to get by for 6 months or so in emergency funds, and maybe even double that.
Hypothetically, anyone can say that cash is wasting away and should be invested, however, I just happened to be cash rish at the start of the Great Recession, and I had real money while everyone else had money in homes that were underwater, in the market that had crashed, and were probably carrying significant credit card debt. People were losing their jobs left and right.
I guess if you have had money in the market the last 20 years and can handle a large drop in value in your portfolio, then I guess have less cash. But if you've been in it for a short time, and a major correction or crash will put your portfolio in the red, then having enough cash to weather a storm might be better. Granted, the Great Recession was some time ago, and you could do the math on what the cash NOT being in the market has cost you, but I knew a lot of people who had wealth that looked good on paper before the crash, and lost a tremendous amount because they couldn't pay bills. I will just never forget it.
People's memories tend to be short, and fall into a trap where they are unprepared for inevitable changes ahead, believing that everything is predictable and will continue as they are today. That is just not the case.
Its a very personal decision. Use what others recommend as a place to start and then crunch your own numbers. Maybe model a scenario on how you would feel if the stock market went down 10%, 20%, 30% for an extended time and how you would do in that situation.